International Research Fellow Awards: Hormonal Control of Seed Germination in Arabidopsis Thaliana

9704233 Steber国际研究员奖励计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Camille M. Steber博士与Peter D. McCourt博士在安大略省多伦多多伦多大学进行为期12个月的博士后研究访问。Steber博士将研究植物激素赤霉素（GA）在控制种子休眠和发芽中的作用。为了确保植物胚胎在母体释放和发芽之间的间隔中存活，种子积累营养储备，进入休眠和耐干燥状态。有一些机制可以确保种子只有在为幼苗生长提供有利环境的“休眠打破”条件下才能发芽。拟南芥（Arabidopsis thaliana）需要植物激素ABA （abscisic acid， ABA）来建立休眠，而GA则需要植物激素来结束休眠并诱导种子萌发。我们对赤霉素诱导发芽的机制知之甚少。该项目将侧重于利用两种遗传方法了解控制种子中GA接受性的机制：第一种方法将通过筛选aba不敏感突变的抑制因子来识别GA不敏感突变；第二种方法将确定当基因过度表达时，在缺乏外源GA的情况下抑制GA营养不良基因gal-3发芽的能力。对遗传响应的这种理解将在农业领域有重要的应用。McCourt博士是北美为数不多的研究ABA和GA在控制种子休眠和发芽中的作用的研究人员之一。他在多伦多大学的实验室将提供一个与包括植物生理学、生物化学和发育在内的广泛的植物生物学专家交流的机会。＊＊＊

9704233 Steber The International Research Fellow Awards Program enables U.S. scientists and engineers to conduct three to twenty four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twelve-month postdoctoral research visit by Dr. Camille M. Steber to work with Dr. Peter D. McCourt at the University of Toronto in Toronto, Ontario. Dr. Steber will investigate the role of the plant hormone gibberellic acid (GA) in the control of seed dormancy and germination. To ensure that plant embryos survive the interval between release from the mother plant and germination, seeds accumulate nutrient reserves and become dormant and desiccation tolerant. There are mechanisms that ensure that seeds germinate only under "dormancy breaking" conditions that provide a beneficial environment for growth of the seedling. In studying the Arabidopsis thaliana, the plant hormone abscisic acid (ABA) is needed to establish dormancy while the GA is needed to end dormancy and induce seed germination. Little is known about the mechanisms by which GA induces germination. This project will focus on understanding those mechanisms governing GA receptivity in the seed using two genetic approaches: the first will identify GA-insensitive mutations using a screen for suppressors of an ABA-insensitive mutation; the second will identify genes which when overexpressed, suppress the inability of the GA auxotroph gal-3 to germinate in the absence of exogenous GA. Gaining this understanding of GA response will have important applications in the area of agriculture. Dr. McCourt is one of relatively few North American researchers who has investigated the role of both ABA and GA in the control of seed dormancy and germination. His laboratory at the University of Toronto will provide an opportunity for interaction with a wide- range of experts in plant biology including plant physiology, biochemistry, and development. ***